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and is a member of the class of compounds termed 2-[4-(diphenylmethyl)-1-piperazinyl]acetic acids. These compounds are useful as antiallergens, spasmolytics, and antihistamines which are generally non-sedating. See U.S. Pat. No. 4,525,358 and The Merck Index, Eleventh Edition, 1989, page 310, entry 2013.
Pseudoephedrine, as well as pharmaceutically acceptable acid addition salts thereof such as the hydrochloride and sulfate salts, is a sympathomimetic drug known by those skilled in the art as a safe therapeutic agent for treating nasal congestion. It is commonly administered orally and concomitantly with an antihistamine for treatment of nasal congestion for the treatment of allergic rhinitis.
Cetirizine and pseudoephedrine can be administered together. The general schedule for administering the two drugs together involves one 10 mg cetirizine tablet per day, plus eight 30 mg immediate-release pseudoephedrine tablets divided into four doses over the course of a day. It is well known, however, that patient compliance with a multiple dose daily administration schedule can be affected by the inconvenience of having to remember to take medicine at numerous, appropriately spaced intervals. It would accordingly be useful if patients could take cetirizine plus pseudoephedrine as a unitary dosage form, such as a tablet, say once-daily or twice-daily, to improve convenience and better ensure patient compliance.